NASA plans to follow a successful and ongoing mission to map Earth's gravity with a quest to glean similar information about the moon.
By measuring shifting masses on Earth, the Gravity Recovery and Climate Experiment, or GRACE, has revealed ice melts at the polar caps, changes in ocean circulation and tectonic plate shifts.
On the moon, scientists will use the same technique to peer beneath the crust to look for a core, if one exists, ancient lava flows and other internal structures. The information is expected to provide details about the moon's evolution and history.
The new mission, called the Gravity Recovery and Interior Laboratory, or GRAIL, may in turn pave the way for a gravity map of Mars and other planets, Alan Stern, NASA's associate administrator for science, said at the American Geophysical Union conference in San Francisco this week.
Like GRACE, the key science instruments for GRAIL are a pair of satellites that fly in formation 137 miles apart. Microwave range finders aboard the spacecraft constantly monitor the tiniest of fluctuations in the distance between them. As the lead craft flies over an area of greater mass, it reacts to the increased gravitational tug before the trailing partner.
The instruments can measure variations as small as a micron, or one-millionth of a meter. A strand of human hair measures about 75 microns in diameter.
By measuring shifting masses on Earth, the Gravity Recovery and Climate Experiment, or GRACE, has revealed ice melts at the polar caps, changes in ocean circulation and tectonic plate shifts.
On the moon, scientists will use the same technique to peer beneath the crust to look for a core, if one exists, ancient lava flows and other internal structures. The information is expected to provide details about the moon's evolution and history.
The new mission, called the Gravity Recovery and Interior Laboratory, or GRAIL, may in turn pave the way for a gravity map of Mars and other planets, Alan Stern, NASA's associate administrator for science, said at the American Geophysical Union conference in San Francisco this week.
Like GRACE, the key science instruments for GRAIL are a pair of satellites that fly in formation 137 miles apart. Microwave range finders aboard the spacecraft constantly monitor the tiniest of fluctuations in the distance between them. As the lead craft flies over an area of greater mass, it reacts to the increased gravitational tug before the trailing partner.
The instruments can measure variations as small as a micron, or one-millionth of a meter. A strand of human hair measures about 75 microns in diameter.
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